In the screen technology, a number of problems are solved by the use of a circular screen, made of woven wire, which is held tightly on a circular tension ring mount and attached by welding or bonding the like to that ring. A related technology involves what is referred to in the industry as "anti-blinding" structures, wherein a device is used to prevent clogging of the openings formed by the woven wire. One such device or structure for performing "anti-blinding" functions relates to the use of hollow rings which are disposed, each with a vertically oriented axis in a manner to clean the interstices of the woven wire by moving around just below the screen. Often, the tension ring holding the woven wire is made with a simple "Z-shape", wherein an upper and lower horizontal flange is connected by a vertical flange, with the screen mounted on the upper horizontal leg whose free end points toward the center of the ring. Such a structure has the disadvantage of a lack of stiffness, but also the disadvantage that, with "anti-blinding" devices as described above, the plastic rings jam up under the upper horizontal leg of the tension ring. Other structures for the same purpose use a hollow tension ring, wherein a hollow square structure is arranged under the upper horizontal leg of the tension ring to prevent jamming, and to add stiffness. However, manufacturing complexities result.
In more detail, when woven wire structures are in the large dimensional category, such as one and one-half feet or more diameter rings, the lack of complexity in manufacturing the tension ring becomes more critical- Furthermore, such large diameter screens are much more difficult to place in the proper tension for the various applications of the structure.
Manufacturing of such tension rings is usually related to two basic steps; namely, a first step involving the forming of the cross-sectional shape of the tension ring, and then, secondly, the rolling of such form into a perfectly circular shape. The complexities noted above take hold most particularly during the rolling process.
In terms of prior art, two Jesse Rosenblum U.S. Pat. Nos. 3,985,065 and 3,792,774, relate to the placing of screens in tension for supporting various materials. However, in both cases, the problem disclosed above concerning jamming during the "anti-blinding" function are not solved by the Rosenblum structures.
Likewise, Moulten U.S. Pat. No. 3,243,042 is also subject to the same drawback.
The Yu Si-Lin U.S. Pat. No. 4,929,346 concentrates more on solving a different set of problems, without addressing the problems solved by the present invention. Thus, the Si-Lin patent does not anticipate the structure of the present invention.